Document Type

Article

Publication Date

2023

DOI

10.1111/gcb.17093

Publication Title

Global Change Biology

Volume

30

Issue

1

Pages

e17093 (1-16)

Abstract

Phytoplankton exhibit diverse physiological responses to temperature which influence their fitness in the environment and consequently alter their community structure. Here, we explored the sensitivity of phytoplankton community structure to thermal response parameterization in a modelled marine phytoplankton community. Using published empirical data, we evaluated the maximum thermal growth rates (μmax) and temperature coefficients (Q10; the rate at which growth scales with temperature) of six key Phytoplankton Functional Types (PFTs): coccolithophores, cyanobacteria, diatoms, diazotrophs, dinoflagellates, and green algae. Following three well-documented methods, PFTs were either assumed to have (1) the same μmax and the same Q10 (as in to Eppley, 1972), (2) a unique μmax but the same Q10 (similar to Kremer et al., 2017), or (3) a unique μmax and a unique Q10 (following Anderson et al., 2021). These trait values were then implemented within the Massachusetts Institute of Technology biogeochemistry and ecosystem model (called Darwin) for each PFT under a control and climate change scenario. Our results suggest that applying a μmax and Q10 universally across PFTs (as in Eppley, 1972) leads to unrealistic phytoplankton communities, which lack diatoms globally. Additionally, we find that accounting for differences in the Q10 between PFTs can significantly impact each PFT's competitive ability, especially at high latitudes, leading to altered modeled phytoplankton community structures in our control and climate change simulations. This then impacts estimates of biogeochemical processes, with, for example, estimates of export production varying by ~10% in the Southern Ocean depending on the parameterization. Our results indicate that the diversity of thermal response traits in phytoplankton not only shape community composition in the historical and future, warmer ocean, but that these traits have significant feedbacks on global biogeochemical cycles.

Rights

© 2023 The Authors. Global Change Biology published by John Wiley & Sons Ltd.

This is an open access article under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.

Data Availability

Article states: "The Darwin model used in this study is available through https://github.com/darwinproject/darwin3, and the physical model is available through https://mitgcm.org. Outputs from model simulations are archived on the Harvard Dataverse (Anderson, 2023). Code to reproduce these analyses are available on GitHub (https://github.com/sianderson/Thermal_trait_parameterization) and archived at Zenodo (Anderson & Fronda, 2023)."

Original Publication Citation

Anderson, S. I., Fronda, C., Barton, A. D., Clayton, S., Rynearson, T. A., & Dutkiewicz, S. (2023). Phytoplankton thermal trait parameterization alters community structure and biogeochemical processes in a modeled ocean. Global Change Biology, 30(1), 1-16, Article e17093. https://doi.org/10.1111/gcb.17093

ORCID

0000-0001-7473-4873 (Clayton)

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